Showing posts from March, 2014

IO calibrate statistics are missing in oracle explain plan

IO calibrate statistics are missing  in explain plan, then below mentioned steps should be executed one by one :-

set these parameters

1.alter system set filesystemio_options=asynch scope=spfile
2.alter system set disk_asynch_io = true scope=spfile;
3.bounce the db
4.Ensure asynchronous I/O is enabled on all datafiles and tempfiles. The following query can be used to            verify asynchronous I/O for these files.

col name format a50
select name,asynch_io from v$datafile f,v$iostat_file i
where f.file#=i.file_no
and (filetype_name='Data File' or filetype_name='Temp File');
/ the calibration procedure :-

  l_max_iops        PLS_INTEGER;
  l_max_mbps        PLS_INTEGER;
  l_actual_latency  PLS_INTEGER;
  DBMS_RESOURCE_MANAGER.calibrate_io (
    num_physical_disks => 1,
    max_latency        => 20,
    max_iops           => l_max_iops,
    max_mbps           => l_max_mbps,
    actual_latency     => l_actual_late…

change oracle database name using nid

First of all start your database in mount state . Here I am changing the database name from orcl to orcl4. Then perform below steps :-

[oracle@host01 dbs]$ sqlplus sys/sys as sysdba

SQL*Plus: Release Production on Fri Mar 7 12:09:36 2014

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select open_mode from v$database;


SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

[oracle@host01 dbs]$ nid target=sys/sys DBNAME=orcl4

DBNEWID: Release - Production on Fri Mar 7 12:14:08 2014

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to database ORCL (DBID=1305795399)

Connected to server versi…

Things to consider before moving table

The following thing can be potential problem for big size table move .

1. No transaction should access those tables which you are going to move otherwise there will be ORA error on application side .So better to use dbms_redifnation in this case.( dbms_redifnation is available only EE edition) .

2. Time estimation can be go wrong .It may be due to different storage type used ( some times in some scenario the moving table reside on attached hard disk level file system and target reside on NAS or SAN ). I have seen that even 100GB of table takes time around 4 hours although target tablesapce and source tablespace were on different mount point but on same storage ( it was SAN ) .

3. Always use DBverify command to check block level corruption on target datafile before moving large tables .Otherwise it stuck in the middle of operation and some times it gets failed . can not use index rebuild on BITMAP index on partition table , if it is invalid state , you have to drop and rebuild …

configuring archive and backup

1.Log on the target server and find out database is in archive log or not :-

Export ORACLE_SID=<database_name>
Sqlplus / as sysdba
SQL> archive log list;
Database log mode              No Archive Mode
Automatic archival             Disabled

2.Create respective directories for backup in the name of database on the backup location and grant permission on it .

mkdir –P /backup/$ORACLE_SID/flash_recovery_area

chmod –R 777 /backup/$ORACLE_SID/flash_recovery_area

chown –R oracle:oinstall /backup/$ORACLE_SID/flash_recovery_area

3.Configure database in archive log, recovery area ,recovery location  :-

SQL>create pfile from spfile;
(take backup of pfile)

SQL> select * from v$recovery_file;
(Here none of the datafile should be there)

SQL> show parameter recovery_file_dest;

SQL> alter system set log_archive_dest_1='LOCATION=/backup/$ORACLE_SID/flash_recovery_area' scope = both;

SQL> alter system set db_recovery_file_dest_size=(db_size+archivelog+20%);